Travelling wave-based pilot direction comparison protection for HVDC line

Abstract

SUMMARY As the main protection of HVDC line, the protection zone of conventional travelling wave protection depends on the predetermined setting value. It also can't detect the high-impedance grounding fault due to its using of data from only one end. To improve the protection performance, a travelling wave-based pilot direction comparison protection is proposed based on the fact that the amplitude of the first backward travelling wave is greater than that of forward travelling wave for a forward fault. The magnitudes of forward and backward travelling wave are integrated, respectively, within a short period following the relay starter has picked up. The ratio of the integral values is used as the fault direction discriminator. If both relays at the two ends of the HVDC line detect it a forward fault, it will be judged as an internal fault, and the faulty pole can be determined by the polarity comparison of aerial and earth mode backward traveling waves. The RTDS-based simulation tests are carried out with consideration of dc filter effect, and the results demonstrate that the proposed scheme can discriminate the internal and external faults rapidly and reliably. It is tolerant of a high resistance coverage and has a specific protection zone. Copyright © 2012 John Wiley & Sons, Ltd.